According to Snapshot from Practice $5\mathrm{.}4,$ a general rule of thumb when it comes to estimating is

Multiple Choice

task duration should not exceed $20$ workdays or at most $40$ workdays

add $25$ percent buffer to your estimates

task duration should not exceed $1$ workday or at most $5$ workdays

task duration should not exceed $5$ workdays or at most $10$ workdays

double your normal estimate