Increase in the focal length of eye lens and Stiffening

Select the number from the given option that can replace the question mark [?] in the following series.

515, 517, 520, 525, 532, 543, 556, ?

Find the missing term :

Study the given pattern carefully and select the number that can replace the question mark [?] in it?

UDGO : FWTL : : MXRC : ?

Find the missing term in the given series:

Select the missing number from the given responses:

M/14 : O/12 : : U/6 : ?

Find the missing term?

Find the missing number.

Find the missing letter.