Thanks for asking question on GMAT section,

Your question was – How will you represent the term 140 with the help of roman numbers?

Your correct answer is- d

Now read this explanation for more clarifications:

According to the rules used for writing the roman numbers,
Letter I represents a value of 1
Letter V represents a value of 5
Letter X represents a value of 10
Letter L represents a value of 50
Letter C represents a value of 100
Letter D represents a value of 500
Letter M represents a value of 1000
∴ 140 can be written as 100 + 40
For 100 we can use the symbol C.

But, 40 cannot be written as XXXX, because we cannot the same symbol more than 3
times consecutively.
∴ We can write 40 as XL

Hence, we can write 140 as CXL in terms of roman numbers.
Hence, the correct answer is option d.