Please answer the multiple choices accurately. Will only like for accuracy

1. What is the maximum length that CNTs should have prior to their introduction into an organism in order to be easily eliminated or expelled? a) 3 um b) 1000 nm c) 400 nm d) 1.5 um 2. The cell viability of several lines exposed to CNTs and as tested in the literature does not decrease significantly even at large concentrations of CNTs and after exposure for the standard duration of: a) 24 hours b) 48 hours c) 72 hours d) Other: 3. Which is the most important safety measure that must be taken during handling of carbon nanotubes? a) Local exhaust b) Impervious gloves c) Mask and filters (respirator) d) Foot coverings