Final answer:
In Seamus Heaney's "Digging", the speaker implies that his father and grandfather's occupations require values similar to those of his own, showing respect for their manual labor and dedication. The correct choice of option is a. is less respectable than his occupation.
Step-by-step explanation:
In the poem "Digging" by Seamus Heaney, the speaker does not imply that the occupation of his father and grandfather is less respectable or less valid than his own occupation. Instead, the poem reflects a deep respect for the manual labor and the dedication his ancestors had for their work, which can be inferred as suggesting that the occupations require values similar to those required of his own occupation as a writer. The speaker looks at his own pen and recognizes it as his tool, as the spade was the tool for his father and grandfather, to dig into his own respective field, which is the literary tradition.