Hey @rajesh512!
Welcome to the forum!
It looks like this is a case of "string-quoting" getting out of hand. It looks like one of the options is missing a closing quote:
–type "FeatureTable[Frequency]
This caused the command line to pass all of this as the type:
"FeatureTable[Frequency] --input-format BIOMV100Format --output-path /Desktop/output\nqiime tools import --input-path RISK_all_samples.biom --type FeatureTable[Frequency]"
Which is the cause of the scary error.
Double check that all of your quotation marks start and end where they should and give the command another shot. Let us know how it goes!