Which of the Following Is a Method for Correlating a Physical

Which of the following is a method for correlating a physical map of a chromosome with a genetic map and/or a cytological map?
1) Genes that have been cloned can be positioned on the cytological map by in situ hybridization
2) Locating clones of genetically mapped genes or RFLPs on the physical map
3) Using PCR to amplify short unique genomic DNA sequences and Southern blots to relate these sequences to overlapping clones on physical maps

A) 1
B) 2
C) 3
D) 1 and 2
E) All of these