Choose the correct options-
(a) Threadlike cytoplasmic strands, running from one cell to another are known as plasmodesmata.
(b) Xylem and phloem constitute the vascular bundle of the stem
(c) First formed xylem elements are described as metaxylem
(d) Radial bundles are mainly found in leaves

(A) a,b true c, d wrong
(B) d true, a,b,c, wrong
(C) c true, a,b,d, wrong
(D) a true ,b,c,d wrong.

Hint:
 A plant has many parts specialized for various functions. Every part is unique starting from the apex to the shoot tip. These strands help in building the connection and possess a specific vascular system for transportation which takes place with the help of vascular bundles.

Complete answer:
Now let’s analyze our options one by one. We will start with our first option,
 (a) Threadlike cytoplasmic strands, running from one cell to another are known as plasmodesmata.
 For this, only knowing the definition of plasmodesmata will suffice.
Plasmodesmata are the thread-like extensions of the cytoplasm or cytoplasmic extensions between two cells which helps in the process of communication and also helps in the process of transportation. So the first given choice is correct.
Now moving on to the next option which is an option
 (b) Xylem and phloem constitute the vascular bundle of the stem.
 As we know that the plants possess permanent complex tissues in the form of xylem and phloem.
Xylem- It performs the function of uptake of fluids especially water along with minerals. It starts from roots and spreads to all parts.
Phloem- It transports the prepared food by chloroplasts to all the other parts of plants. So, it spreads from leaves to all other parts.
So, they perform the function of the vascular bundle (transport system in plants). So our second given choice is also correct.
So far we know that options a and b are correct. Now, let’s move further to our option
(c) First formed xylem elements are described as metaxylem.

We know that organisms undergo growth and plants first undergo primary growth and then attain secondary growth in which vascular cambium is formed which divides the xylem and phloem into secondary structures. Now this xylem divides into protoxylem and Metaxylem.
So, here we can see that the first-formed xylem is Protoxylem and not metaxylem. So, this statement is incorrect.
Now for the next option that is
 (d) Radial bundles are mainly found in leaves.
We already studied what a vascular bundle is, so we can say that it is not present in Leaves but instead it is present in roots and stems. So, this option is also incorrect.

A correct option is an option (A) ie. a,b true c,d wrong.

Note: In plants, there are not only present just radially arranged bundles but two more types of arrangements are visible- Conjoint(Xylem and Phloem are joined together) and Concentric(these are closed because one type surrounds the other).