Replace the underlined tense form with the correct option: If you will work hard you will certainly succeed.
a. work
b. works
c. worked
d. have worked

Hint:The student should read the sentence carefully to understand when the event is supposed to be taking place. Determine the tense of the options and choose the option which agrees with the tense of the sentence.

Complete answer: In this question, it will be helpful for the student to recall the concept of tense. Tense is a grammatical category of verbs used to express distinctions of time. There are three categories of tenses - past, present, and future. The given sentence is in the present tense. The structure/formula of a Simple Present Positive Sentence is – subject + main verb + object.
Let us analyze the options given to us in this question -
Option (a.), 'work', refers to ‘simple present tense in the second person’.
Therefore, option (a.) is correct as here, a condition is presented in the present, which indicates that the answer should be in the present tense. ‘You’ is in the second person thus it is also correct.
Option (b.), ‘works', refers to ‘simple present tense in the third person singular’.
Therefore, option (b.) is incorrect as ‘you’ is in the second person and not third.
Option (c.), ‘worked', refers to ‘simple past tense’.
Therefore, option (c.) is incorrect as a condition is presented in the present, which indicates that the answer should be in the present tense.
Option (d.), ‘have worked', refers to ‘present perfect tense’.
Therefore, option (d.) is incorrect as simple present tense should be used here to indicate a conditional possible happening.
Therefore, option (a) is the correct option.

Note: The Present tense can be classified into 4 types, namely, (i) Simple Present(eg: I go.), (ii) Present Perfect(eg: I have gone.), (iii) Present Continuous(eg: I am going.) and (iv) Present Perfect Continuous(eg: I have gone).